Simple Listing is the one I'd choose because these aren't just common words.
"Unable to do" in one word is "incapable."
Incapable means "unable to do or achieve (something)."
There was chaos because he was the king and there was no heir to inherit the throne. So Merlin placed a spell on a sword and put the sword in a stone. The one that could pull the sword from the stone would become the next king.
I honestly believe that all of the answers are correct, but I think that the most important one of all is rhetorical strategies because narration, description, descriptive meanings etc. (rhetorical strategies) are very important to make the essay sound professional. That’s my opinion. I hope I’m right.